t = readmatrix('E.out', 'FileType', 'text');
figure;
for i = 1:3
    x = t(i*2-1, :);
    yi = t(i*2, :);
    plot(x, yi);
    hold on;
end
l = {'N=10', 'N=40', 'N=160'};
legend(l);
saveas(gcf, '../pic/E.eps');